Glucose consumption and lactate production by tumour cells of the gastric carcinoma cell line 23132/87. (A) Time-dependent glucose uptake. The glucose uptake was measured with the fluorescent deoxyglucose analog 2-NBDG by flow cytometry. Tumour cells were incubated with 0.1 mmol/l 2-NBDG for 10, 30, and 60 min under normoxic conditions. The non-filled curves indicate the proportion of cells incorporating 2-NBDG and the filled curve represents the background staining of cells incubated with 2-NBDG on ice. (B) Concentration-dependent glucose uptake. Tumour cells were incubated with 0.01, 0.1, and 1 mmol/l 2-NBDG for 10 min. The filled curve represents cells incubated without 2-NBDG. (C) The 2-NBDG uptake of gastric carcinoma cells in comparison with HUVEC. The cells were incubated for 10 min with 0.01, 0.1, and 1 mmol/l, respectively. The flow cytometric data represents the total tumour cell population minus dead cells. MFI: Mean fluorescence intensity; ΔMFI = (MFI2-NBDG)-(MFIunstained cells). (D) Lactate production. Lactate concentration in the culture medium was measured as described in Methods. Lactate production by tumour cells and HUVEC depends on glucose concentration in the culture medium but shows an increase in gastric cancer cells. Data in A-D are from one of three independent experiments.